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https://issues.apache.org/jira/browse/HBASE-12411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14216983#comment-14216983
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Hudson commented on HBASE-12411:
--------------------------------

FAILURE: Integrated in HBase-TRUNK #5788 (See 
[https://builds.apache.org/job/HBase-TRUNK/5788/])
HBASE-12411 Optionally enable p-reads and private readers for compactions. 
(larsh: rev 822bcce91e5d80f778c009dcc6d50089276859df)
* 
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/compactions/DefaultCompactor.java
* 
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFile.java


> Optionally enable p-reads and private readers for compactions
> -------------------------------------------------------------
>
>                 Key: HBASE-12411
>                 URL: https://issues.apache.org/jira/browse/HBASE-12411
>             Project: HBase
>          Issue Type: Improvement
>          Components: Performance
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>             Fix For: 2.0.0, 0.98.9, 0.99.2
>
>         Attachments: 12411-v2.txt, 12411-v3.txt, 12411-v4.txt, 12411.txt
>
>
> In the light of HDFS-6735 we might want to consider refraining from seek + 
> read completely and only perform preads.
> For example currently a compaction can lock out every other scanner over the 
> file which the compaction is currently reading for compaction.
> At the very least we can introduce an option to avoid seek + read, so we can 
> allow testing this in various scenarios.
> This will definitely be of great importance for projects like Phoenix which 
> parallelize queries intra region (and hence readers will used concurrently by 
> multiple scanner with high likelihood.)



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